jigdog

Yesterday while crusing slow with light load at slow speed my throtle started going up and down in rpm with my foot off the pedal.this has happened off and on now for 3 months. i have grounded the apps to the batt and added a jumper from the apps to the pcm so the pcm gets its signal straight from the apps.it has worked fine for most of that time . the jumper was done about 3 months ago and the only time this happens is when the engine temp is up to at least 180 and then it will do it once or twice then stop doing it.my bat terminals are clean and sealed and i get no codes off the odometer when checked.i am thinking maybe i have a ground issue that flares when the engine temp get up . can anyone help with were to look for another ground issue.